Coil construction



Sept. 20, 1932. w Q SCHNE|DER ETAL 1,878,606

con. CONSTRUCTION Filed July 20. 1928 Inventor/a Fil 1 FE1-L Hark/wonPatented Sept. 20, 1932 UNITED STATES PATENT OFFICE WILLIAM G. SCHNEIDERAND HARRISON H. EATON, OF TOLEDO, OHIO, ASSIGNORS TO THE ELECTRICAUTO-LITE COMPANY, OF TOLEDO, OHIO, A CORPORATION OF OHIO i COILCONSTRUCTION Application led July 20, 1928. Serlal No. 294,143.

This invention relates to induction coils and particularly to coils ofthe high tension discharge type such as are used in ignition systelnsfor internal combustion engines and 5 in the operation of high frequencyapparatus. It is well known in the art that in devices of thischaracter, an interrupted or alternating current in a primary winding ofcomparatively few turns is stepped u or increased into a current ofgreatly ampliged voltage by means of a secondary windin of many turns.In the production of an e cient induction coil of this character, it isnecessary to concentrate the wire of the seconda winding into a smallcompass so as to posltion practically all or at least the greater partof it inside the magnetic field of the primary winding and core. Thisconstruction necessarily places a limit upon the amount of insulationwhich can be used between the juxtaposed layers and between the adjacentturns in the same layer. Another condition which is to be encounteredlies in the fact that if an insulation of high specific inductive l5capacity be employed, the result is to amplify to an alarming factor thecondenser effect between the successive layers of wire.

Ve have found that during the operation of the coil of this characterthere is superm imposed upon the ordinary and generally describedsecondary action, a static surging effeet wherein the amount ofelectricity involved is extremely small, but its electromotive forcecomparatively high. This effect reaches a maximum value or intensity inthe region adjacent the extremities of the secondary coil structure. Theeffect of this high potential static charge appears to seek a paththrough the insulation after which the direct secondary discharge ofgreater quantity of lower potential is enabled to pass with its wellknown heating and disintegrating effect. In a coil wound in the normalmanncr, the insulation adjacent the extremities of the secondary windingis none too high lwtween the adjacent layers; and break downs, burningor puncturing of the insulation usually occurs at these points.

This invention contemplates the utilization "0 of novel means forpreventing a puncturing or breaking down of the insulation withoutenlarging the size of the coil structure and the invention comprehendsthe spacing of certain layers of wire, and maintaining the amount ofinsulation between the successive layers substantially uniform wherebythe electric stresses are decreased and the condenser eiect between theseveral layers of wire is substantially reduced.

The invention has for a further object to provide a coil structure ofthis character wherein the elements of the coil per se are compactlyassembled, forming a very elicient and inexpensive structure.

Further objects and advantages are within the scope of this inventionsuch as relate to the arrangement, operation and function of the relatedelements of the structure, to various detailsof construction and tocombinations of parts, elements per se, and to economies of manufactureand numerous other features as willv be apparent from a consideration ofthe specification and drawing of a form of the invention, which may bepreferred, in which:

Figure 1 is a vertical, longitudinal, sectional view through the coil ofour invention;

Figure 2 is a detail sectional view taken substantially on a line 2 2 ofFigure l;

Figure 3 is an enlarged fragmentary detail view of a portion of the coilstructure;

Figure 4 is' an enlarged fragmentary dctail view of a portion of thecoil structure showing the method of securing the leads to the windings.

We have shown our invention as embodied in an ignition coil suitable foruse in the ignition system of an internal combustion engine, but it isto be understood that we do not wish to limit our invention to theparticular embodiment illustrated, and that we contemplate the use ofour invention wherever the same may be found to be applicable.

Referring more particularl to Figure 1, the coil structure comprises aaminated core 5 which is formed by assembling a plurality of iron orsteel strips into a compact struc. ture which is subsequently insertedinto tubes 6 and 8 of suitable insulating material, the

tubes 6 and 8 being surrounded by a second insulating tube 7.Surrounding the tube 7 is a secondary Winding 9, the construction ofwhich will be hereinafter described in further detail.

Surrounding the secondary winding 9 is an insulating tube 11 upon whichis wound a primary winding 12 superposed upon the secondary winding asshown in Figure 1. Surrounding the primary winding 12 is anotherinsulating tube 14, the complete winding and core assembly beingsupported and housed within a cylindrical metallic casing 16. Interposedbetween the insulating tube 14 and the walls of the casing 16 is aplurality of metallic laminations 17 which are assembled as shown indetail in Figure 2. These laminations serve to form a path for themagnetic lines of force set up in the core andwindings thus making avery efficient structure. The several laminations 17 are of semicylindrical form, the ends being slightly separated to form a gap whichserves to decrease or reduce eddy currents.

One end of the core 5 is received into a bore in a supporting member 18which may be of any suitable insulating material as, for example,porcelain which possesses hi h insulating qualities. One end of thecasing 16 is adapted to be enclosed by means of a circular cover 20.

The other end of the casing 16 is enclosed by means of a metallic cap 22which may be secured to the casing in any suitable manner as bysoldering illustrated at 23, the crown of the cap being provided with anenlarged bore which receives a member 24 of porcelain or otherinsulating material, the inner end of said member having afrusto-conical bore which receives and supports the other end of themagnetic core structure 5. The outer extremity of the porcelain member24 is provided with a bore 26 which contains a metallic thimble 27forming the high tension terminal for the secondary winding, the thimblebeing connected to one end of the winding by means of a lead 29.

We have found that in order to prevent a derangement or loosening of thewire of the secon ary winding it is desirable to pass the lead 29through a small aperture in the outer insulating tube 7 surrounding thecore 5 as particularly shown in Figure 4, the lead passing between theadjacent'ends of the tubes 6 and 8. This arrangement serves as holdingmeans for the end of the wire at the beginning of the winding operationand also tends to prevent an accidental breaking of the winding lead.

Positioned on either side of the orcelain member 24 are the primarytermina 30 and 31 connected to the respective ends of the primarywindings by means of leads 32 and 33. The terminals 30 and 31 areprovided with threaded tenons 35 which are adapted to pass throughenlarged openings in the cap 22, the tenons being s aced from the ed ofthe opening and wit the use of insulating washers 36 positioned oneither side of the cap 22 a metallic connection hetween the terminals 30and 31 and the cap 22 is avoided.

The coil structure is assembled before placing the cap 22 in positionand any remaining cavities are filled with an insulating compound 37which is impervious to moisture and which serves as an additional meansto prevent derangement of the parts in the casing. The cap 22 may besoldered or otherwise iixedly secured to the casing 16.

The secondary winding structure will now be described in further detail.In the beginning of the operation of winding the secondary coil upon thetube 7, the first few layers of wire 40, preferably three or four, areso arranged that the individual turns or convolutions of wire are spacedone from the other whereby fewer number of turns are inclosed in thespace occupied by the winding per se, the several layers of wire beingseparated by suitable insulating strips. The remaining layers of wire,with the exception of the outermost three or four layers of thesecondary winding, are close wound, i. e. the individual convolutionsare substantially in contact with each other. The outer layers of wireare s aced similarly to the inner layers of wire, t e several layersbeing separated by means of suitable strips of insulatmg material. It isto be understood that all the layers of wire are insulated one from theother and in the form shown, substantially the same amount of insulatingmaterial is used between each successive layer irres ective of whetherthe wire is close woun or space wound.

We have distributed the dielectric stresses produced by high inductiveeffects and os cillatinv currents close to the magnetic corel by spacingthe turns or convolutions of the innermost and outermost layers of thesecondary winding whereby a material saving is effected in the copperwire and insulating material used in the winding.

We have found it desirable in order to produce a coil of higheificiency, to decrease the number of turns in each successive layer inthe primary winding, however, the several layers of the primar windingmay be wound with an equal num r of turns which does not materiallyinterfere with the successful operation of the coil.

It is apparent that, within the scope of the invention modifications anddifferent arrangements may be made other than is herein disclosed, andthe present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

What we claim is:

1. In a coil structure of the character disclosed comprising a corestructure formed of a ,plurality-of flat metallic strips; insulatingmeans surrounding said core; primary and secondary windings superposeupon said core structure; a metallic casing surrounding said core andwindings; a plurality of semicylindrical metallic laminations interposedbetween said casing and said windings; a metallic cap for said casing;said metallic cap having an insulating member centrally disposedthereof; a metallic element carried by said insulating member andforming a terlminal for one of said coils; and a pair of coil terminalsinsulatingly supported upon said metallic cap.

2. In an ignition coil of the character disclosed comprising a corestructure insulating means surrounding said core, yprimary and secondarywindings superposed upon said core structure, said secondary windingcomprising a plurality of layers of turns of wire; uniforml insulationbetween said layers; the turns of wire being closely wound in thecentral layers of said winding and, spaced apart at the beginning andend layers thereof as means for preventing a charge of high potentialstatic from causing breakdown in said insulation; a casing surroundingsaid core hnd windings; a pluralit of lamlnations between said windingsan said casing; a cap for said casing, said cap supporting the terminalsfor the ignition coil.

3. In a coil structure of the character disclosed comprising a laminatedcore structure; lnsulating means extending longitudinally of andsurrounding said core; an insulating member having a recess into whichone end of said core extends; primary and secondary windings superposedupon said core structure, said secondary being inside said primar andsaid core extending beyond the ends o said windings; said secondarywinding comprising a plurality of layers of turns of wire; insulationbetween said layers; means associated with an end layer of saidsecondary winding `for preventing a charge of high potential static fromcausing breakdown in said insulation; a casing surrounding said core andwindings; a curved structure between said windings and said casingarranged to prevent eddy current formations; a cap for said casing; aninsulating member for the other end of said core having a recess intowhich said core extends; a mctallic element carried by said insulatingmember constituting a terminal for one of said windings; and a pair ofcoil terminals insulatingly supported upon said cap and insulatinUcompound filling the remaining voids at either end of said coil.

4. In a coil structure of the character disclosed comprising a corestructure; insulating means surrounding said core, primary and secondarywindings superposed upon said core structure, said secondary windingcomprising a plurality of layers of turns of wire;

insulation between said layers extendingbeyond said windings; the turnsof wire being closely wound in the central layers of said winding andspaced apart at the beginning and end layers thereof; means associatedw1th an end layer of said secondary winding for'preventing a charge ofhigh potential static from causing breakdown in said insulation; acasing surrounding said core and windings; a plurality of laminationsbetween said windings and said casing; a cap for said casing; said caphaving an insulating member for said core and having a portion thereofextending into said layer insulation; a metallic element4 carried bysaid insulating member constituting y'a terminal for one of saidwindings; and a pair of coil terminals insulatingly supported upon saidcap.

5. In a. coil structure of the character disclosed comprising a corestructure; insulating means surrounding said core; a secondary windingsuperposed upon said core structure; a primary winding superposed onsaid secondary winding; said secondary winding comprising a plurality oflayers of turns of wire; insulation between said layers; meansassociated with an end layer of said secondary winding for preventing acharge of high potential static from causing breakdown in saidinsulation; a casing surrounding said core and windings; a plurality ofsemi-circular lcurved separate laminations shaped to fit around saidprimary winding and located between said winding and said casing; meansto prevent eddy current formations in said laminations; a cap for saidcasing; said cap having an insulating member for said core; a metallicelement carried by said insulating member constituting a terminal forone of said windings; and a' pair of coil terminals insulatinglysupported upon said cap.

6. In a coil structure of the character disclosed comprising a corestructure; primary and secondary windings superposed upon said corestructure said windings being shorter than said core, said secondarywinding comprising a plurality of layers of turns of wire; insulationbetween said layers; means associated with an end layer of saidsecondary winding for preventing a charge of high potential static fromcausing breakdown in said insulation; insulation tubing surrounding thecore structure which extends beyond said winding, said tubing alsoextending into the said winding structure; a casing surrounding saidcore and windings; a plurality of laminations between said windings andsaid casing; a cap for said casing, said cap having an insulating memberfor said core a metallic element carried by said insulating memberconstituting a terminal for one of said windings; and a pair of coilterminals insulatingly supported upon said cap.

In an ignition coil of the character disclosed comprising a corestructure; insulatizo ing means surrounding said core; primary and`secons'iai! windings superposed on said ocre structure insulatedtherefrom, said secondary winding comprising a plurality of layers ofturns of wire; sheet insulation between said iayers; means for reventmg1a charge or" high potential static om causing break down in saidinsulation; a casing surrounding said core and windings; metallic sheetmaterial between said windings and said casing forming an outer magneticfield; acap for said casing, said cap supporting the terminals for saidcoil; and means for securin the cap to said casino'.

8. n a coil structure of the character disclosed comprising a corestructure; insulating means extending longitudinally of and surroundingsaid core; an insulating member having a recess into which one end ofsaid core extends; primary and secondary windings superposed upon saidcore structure, said secondary winding being inside said primary windingand comprising a plurality of layers of turns of wire; insulationbetween said layers; means associated with an end layer of saidsecondary winding for preventing a charge of high potential static fromcausing break down in said insulation; a casing surrounding said coreand windings; a curved structure between said windings and said casingarranged to prevent eddy current formations; an insulating memberadjacent to the other end of said core having a recess into which saidcore extends; a metallic element carried by said insulating memberconstituting a terminal for one of said windings; a plurality of coilterminals adjacent to said metallic element and insulated therefrom; andinsulatin compound filling the voids -between the e ements of the coilassembly.

9. In a coil structure of the character disclosed comprising amagnetizable core structure; primary and secondary windings superposedupon said core structure insulated therefrom, said secondary windingcomrising a plurality of layers of turns of wire; insulation betweensaid layers extending beyond said windings; means associated with an endlayer of said secondary winding for preventing a charge of highpotential static for causing break down in said insulation; a casingsurroundin said Acore and windings; sheet material etween said windinand said casing; a cap for said casing said cap having an insulatingmember provided with a terminal for said coil and extending within thecasing adjacent said layers of insulation; and a plurality of coilterminals supported upon said cap.

10. In a coil structure of the character disclosed comprising a corestructure; insulating means surrounding said core; a secondary windingsuperposed upon said core structure; a primary winding supersed u onsaid secondary winding, and insulate therefrom, Said secondary windingcomprising a plurality of layers of turns of wire; substantially uniforminsulation between said layers; means associated with an end layer ofsaid secondary winding for preventing a charge of high potential staticfrom causing brea down 1n said insulation; a tubular casing surroundingsaid core and windings; metallic sheet material shaped to fit aroundsaid primary winding and located between said winding and said casing,providing an outer magnetic field; means to prevent eddy currentformations in said sheet material; a cap for the one end of said casing,said cap having an insulating member extending within the casing andcarrying means on the outside thereof constitutin a terminal for one ofsaid windings; a pair of coil terminals supported upon said cap; andmeans to secure said cap to said casing.

l1. In a coil structure of the character disclosed comprising a corestructure; primary and secondary windings superposed said corestructure; said windings being shorter than said core, said windingscomrising a plurality of layers of turns of wire; insulation betweensaid layers; means associated with an end layer of said secondary twinding for preventing a charge of high potential static from causingbreak down in said insulation; tubing surrounding the Core structureinsulatingly supporting said windings from said core; a tubular casingsurrounding said core and windings; metallic sheet material between saidwindings and said casing; a cap for said casing, said cap supporting theterminals for the coil; and means to secure said ca to said casing.

In testimony whereo we aix our signatures.

WILLIAM G. SCHNEIDER. HARRISON H. EATON.

upon

.A li

